1. Field of the Invention
The present invention relates to a base film of a tape for a digital compact cassette (hereinafter referred to as "DCC") which is excellent in running stability and electromagnetic conversion characteristics.
2. Description of the Related Art
DCC is a digital recording audio cassette system which was developed by Philips (the Netherlands) and is being practically used. Characteristics of DCC reside in that DCC is interchangeable with an analog recording type compact cassette different from a digital audio tape (DAT) since DCC does not use a rotational head but uses a fixed head for recording and reproducing, and that a DCC tape has the same tape width and uses the same tape speed as an analog recording type compact cassette tape.
A recording/reproducing head for DCC is a so-called multi-track thin layer head and has 9 channels (8 channels+1 channel). A width of each track is 185 .mu.m, and each guard band width is 10 .mu.m. Then, the DCC tape should have more accurate tracking against the head and better head touch than the conventional compact cassette tape.
In the case of the conventional compact cassette tape, improvement of running properties is highly desired. In addition to this, the DCC tape should have the good head touch. To satisfy these requirements, improvement of the base film is greatly required.
A recording density in the DCC tape is very high and about 1 .mu.m, while that of the conventional compact cassette tape is about 8 .mu.m. In view of such high recording density, a surface roughness of the base film of the DCC tape should be small enough to cope with digital recording.